Rotary impact power tool



Aug. 11, 1959 s. B. MAURER ROTARY IMPACT POWER TOOL 2 Sheets-Sheet, 2

Filed June 14, 1957 INVENTUR. SPENCER BMAUREW United States Patent ROTARY IMPACT POWER TOOL Spencer 13. Manrer, Novelty, Ohio Application June 14, 1957, Serial No. 665,854 23 Claims. (Cl. 81-523) This invention pertains generally to a rotary power device wherein unlimited rotation of the driven member in one direction is effected by limited oscillatory rotation of the motor, and more specifically to a rotary impact tool such as a wrench wherein a hammer is oscillated with respect to an anvil and the impact surfaces of the hammer and anvil are always in the same path of rotation.

An object of the present invention is to provide an impact wrench which can be electrically driven, or pneumatically driven, and wherein the number of parts is kept to a minimum resulting in relatively inexpensive manufacture.

A further object of the present invention is to provide an impact wrench whose hammer and anvil jaws always lie in the same path of rotation so that the jaws are always in proper alignment for engagement with each other, thereby obviating the difficulties which are prevalent in the prior art tools, namely chipping of the impact sur: faces due to occasional mismating of the jaws and high wear rate of the jaws due to frictional forces as the jaws are pulled out of engagement with each other.

Another object of the present invention is to provide an impact wrench wherein there is no relative disengaging motion between the hammer and the anvil thereby obviating many parts which were necessary in prior art tools to cause the disengaging motion of at least a portion of the hammer.

A further object of the present invention is to provide an impact tool wherein the hammer mechanism is a single piece of metal and consequently is very strong yet inexpensive. For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

With reference to the drawings there is shown in Figure 1 a cross-sectional view taken longitudinally through the wrench.

Figure 2 is a front view of the wrench shown in Figure l with the handle portion removed.

Figure 3 is a sectional view taken along line 3-3 of Figure 1, with the housing removed.

Figure 4 is a sectional view taken along line 4-4 of Figure 1, with the housing removed.

Figure 5 is a sectional view taken along line 5-5 of Figure l, with the housing removed.

Figure 6 is an exploded view showing the various parts of the impact tool in their relative position and with the housing removed.

An aspect of the present invention lies in the provision of a rotary power device such as an impact wrench or other rotary power tool, which may be electrically or pneumatically driven, and wherein the device comprises a housing with massive rotor means and a stator means or reaction member means mounted within the housing for rotation, and mounted for rotation with respect to each other. The motor acts on the rotor means and on the reaction member means to establish relative rotation Patented Aug. 11, 1959 therebetween, Automatic reversing means are associated with either the rotor means or the reaction member means to impart oscillatory rotation between them. An overrunning clutch is mounted between the housingand the reaction member means to allow the reaction member member means to rotate only in one direction relative to the housing. An output shaft is provided and there are means in engagement with the reaction member means and in engagement with the output shaft to cause the output shaft to rotate in the one direction.

Another aspect of the present invention lies in the provision of a rotary impact tool made in accordance with the above description wherein the hammer and anvil jaws are always mounted in the same path of rotation and wherein means are provided for reversing the tool so that it can impact either in a foreward or a reverse direction.

Another aspect of the present invention lies in the provision of a rotary power tool comprising a rotor and a reaction member means each mounted for rotation withing a housing, the reaction member means being concentric with respect to said rotor and with respect to said housing. An output shaft extends from the housing and means are mounted within the housing for causing the rotor and the reaction member means to alternately drive the output shaft only in one direction.

With reference to Figure l, the rotary power device of this invention comprises a housing 10 having an output shaft 11 joumaled in the forward end of the tool by the sleeve bearing 12. A massive rotor means indicated generally by the reference character 13 is mounted for rotation in the forward end of the tool and comprises a massive hammer 14 having an impact jaw 1 always in the same path of rotation as an inpact receiving jaw 16 mounted on the anvil member 17. The forward end of the rotor shaft 18 is joumaled in the anvil 17 and the rearward end of the rotor shaft 18 is mounted by means of bearing 22 in a housing bushing 20 mounted in the housing mem ber 10. The rotor shaft 18 supports the hammer member 14 for rotation within the housing 10, the rotor shaft 18 having a splined or hex section 18' at the location of the hammer means to provide a driving connection.

The rotor shaft 18 has a central or hub portion 19 which is larger in diameter than its forward end. The rearward end of the rotor shaft 18 has a bore 23 communicating with a passageway through the housing bushing 20 to the air supply to the tool. The hub 19 of the rotor shaft is slotted at 24 and a tiltable vane 25 is loosely mounted in the slot 24. At the forward end of the hub 19 there is an end plate 26 mounted around the rotor shaft 18. Between the end plate 26 and the hub 19 there is positioned a slide valve member 27 having a pair of cars 28,29. At the rearward end of the hub 19 there is a rear end plate 30. Mounted between the forward end plate 26 and the rear end plate 30 and surrounding the hub 19 there is a cylinder 31. The tiltable vane 25 mounted in the valve slot extends outwardly into engagement with the internal diameter of the cylinder 31. A stationary vane 33 is mounted in a slot 34 in the cylinder member 31, with a small flat leaf spring 32 positioned between the cylinder 31 and the vane 33 to maintain the vane in contact with the hub 19. The stationary vane 33 extends inwardly from the slot 34 into'sealing engagement with the hub 19 of the rotor shaft 18. A pair of limiting arms 36, 37 are connected to the cylinder 31 by means of a plurality of bolts 38 which extend through the forward end plate 26 and into threaded engagement with the rear end plate 30 for connecting together the reaction member means comprised of the cylinder 31, the end plates 26 and 30, and the limiting arms 36 and 37. The arms 36, 37 extend forwardly from end plate 26 beyond the hammer 14, and the ends of the arms 36, 37 lie in the circumferential path of motion of the jaw 16 of the anvil member 17.

The rear end plate 30 includes a rearwardly extending hub 40. Around the hub 40 there is mounted an overrunning spring clutch 41 having two end lugs 42, 43, and a reversing disc 45 is mounted around the housing bushing 20 between the rear end of the housing and the overrunning spring clutch 41. A reversing lever 46 is connected to the reversing disc 45 and extends through a slot 47 in the housing 10. A pair of lug stop pins 50, 51 extend through the housing 10 and project into the annular space around the overrunning spring clutch 41. A movable finger 53 is connected to the reversing disc 45 and is located between the end lugs 42, 43 of the overrunning spring clutch 41. The movable finger 53 is positioned with the motion of the reversing disc 45 to a forward extreme position or a reverse extreme position. As is shown in Figure 3 the tool is in its forward position with the movable finger 53 holding the end lug 43 against the lug stop pin 51. In this position the overrunning spring clutch 41 permits the reaction member means to rotate with respect to the housing 10 only in a forward direction. When the reversing disc 45 is moved to its extreme reverse position the movable finger 53 engages the end lug 42 and holds it against the lug stop pin 50. In this reverse position the overrunning spring clutch 41 permits the reaction member means to move with respect to the housing 10 only in the reverse direction.

Air is supplied to this tool through an inlet port 60 and is admitted to a passageway 61 by means of the throttle valve 62. The passageway 61 extends into the interior of the housing bushing and the air passes through the bore 23 in the rear end of the rotor shaft 18. The live air is then admitted to the space between the hub 19 of the rotor shaft and the cylinder 31 through the slot 24 in which the tiltable vane 25 is loosely positioned. It will be seen in Figure 4 that the annular space between the hub 19 and the cylinder 31 is divided into two portions 63, 64 (Figure 4) by means of the stationary vane 33 and the tilting vane 25. 65 and 66 are provided in the forward end plate 26 for exhausting the annular chamber 63, 64 to atmosphere through exhaust port 67 in the housing 10. The slide valve member 27 moves around the hub 19 with respect to the exhaust ports 65 and 66 to cover up one or the other of the exhaust ports. The slide valve member 27 is moved with respect to the exhaust ports by means of the hub member 19. One specific way of moving the slide member 27 is to have the tiltable vane 25 engage either the ear 28 or the car 29 and move the slide valve 27 as the hub member 19 is rotated.

Live air from the port 23 flows through the slot 24 and depending on the position of the tiltable vane 25 and the slide member 27 will put positive air pressure in either chamber 63 or 64 to cause motion of the rotor hub 19 in one direction or the other.

Figure 4 shows the mechanism at the moment of impact. The exhaust port 66 is closed, the exhaust port 65 is open, air in the chamber 63 is quickly reduced to substantially atmospheric pressure, due to the loose fit of the tiltable vane 25 in the slot 24 air pressure builds up in chamber 64 causing the tiltable vane to tilt toward the car 28 on the slide valve member 27. This admits live air in large quantities to chamber 64 and forces the tiltable vane and the hub member 19 to rotate in a counterclockwise direction. The tiltable vane 25 engages the ear 28 and rotates the slide valve member to close xhaust port 65, substantially simultaneously opening e exhaust port 66. This connects the chamber 64 to mosphere and chamber 63 is sealed. The tiltable vane 25 and rotor hub 19 continue to rotate in chamber 62., due to the inertia built up in the hammer member 14 as air pressure in chamber 63 increases, causing the tiltable vane 25 to shift to the opposite side of slot 24 in hub 19, thus providing a full opening for air under Two exhaust ports pressure to chamber 63. The rearward motion continues until the kinetic energy of the hammer assembly has been absorbed in compressing air in chamber 63 at which time forward or clockwise motion of the rotor assembly begins. A short time thereafter the tiltable vane contacts car 29 of the slide valve 27, and then moves the slide valve 27 until the exhaust port 66 is closed, at which point the hammer jaw 15 contacts the anvil jaw 16 to deliver an impact blow. During the retracting stroke when the hammer jaw is being moved backward away from the anvil jaw the reaction torque on the reaction member means is in a forward or clockwise direction and causes the overrunning spring clutch 41 to slip, allowing the reaction member means to rotate until the limiting arm 37 contacts the anvil jaw 16. During the portion of the stroke while the hammer is being decelerated in its backward movement and again rapidly accelerated in a forward movement, the reaction torque on the reaction member means is in a backward or counterclockwise direction but no motion relative to the housing can occur due to the gripping of the overrunning clutch 41.

When there is great resistance to motion on the output shaft 11 there is a correspondingly large rebound of the hammer from the anvil during impact, which adds to the motor torque in retracting or driving the hammer backwards. Under other conditions of operation where there is little or no resistance to rotation imposed on the output shaft 11, the anvil will be driven forward by the blow of the hammer, and the annular chamber 64 then acts 'as an air cushion as the vane 25 compresses air in this chamber. This has the etfect of providing a forward or clockwise torque on the reaction member means and, of course, also drives the anvil 16 in a forward direction. The limiting arms 36 and 37 limit the motion of the anvil relative to the reaction member means so that the tiltable vane 25 and the stationary vane 33 can never come in contact with one another. When the rotor and hammer are being driven in a backward direction by the motor the reaction member means is being driven in a forward direction as previously mentioned until the limiting arm 37 contacts the anvil jaw 16, and if the resistance to rotation of the output shaft is low the reaction member means will actually drive the output shaft in a clockwise direction until the tiltable vane moves the slide valve 27 to close exhaust port 65 and cause reversal of the motor torque.

While there has been described what is at present considered to be the preferred embodiment of this invention, it will be obvious to those skilled in the art that various changes-and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

I claim:

1. A rotary impact power device comprising, in combination, a housing, massive rotor means and reaction member means mounted within said housing for rotation with respect thereto, and mounted for limited rotation with respect to each other, a motor acting on said rotor means and said reaction member means to establish rotation therebetween, automatic reversing means associated with one of the aforesaid means to impart oscillatory rotation between said rotor means and said reaction member means, an overrunning clutch mounted between said housing and said reaction member means to restrict the motion of the reaction member means relative to said housing effectively to one direction, an output shaft, and means in engagement with said reaction member means and in engagement with said output shaft for causing said output shaft to rotate in the said one direction.

2. A rotary impact power device as set forth in claim 1, further characterized by said overrunning clutch being reversible, and other reversing means for acting on said overrunning clutch to cause said reaction member means to rotate efiectively in the reverse direction relative to said housing when so reversed. l

3. A rotary impact power device as set forth in claim 1, further characterized by said device being an impact device and by said massive rotor means comprising a hammer and said output shaft comprising an anvil, limited lost motion means interconnected between said rotor means and said output shaft to allow said hammer means to deliver a series of impact blows to the anvil in the same direction of rotation as the reaction member means is urging the anvil.

4. A rotary impact power device asset forth in claim 3, further characterized by said overrunning clutch being reversible, and other reversing means for acting on said overrunning clutch to cause said reaction member means to rotate effectively in the reverse direction relative to said housing when so reversed.

5. A rotary impact power device, comprising, in combination, a housing; massive rotor means and reaction member means mounted within said housing for rotation with respect thereto and mounted for rotation with respect to each other; a motor acting on said rotor means and said reaction member means to establish rotation therebetween, an output shaft, first lost motion means connecting said output shaft in driving engagement with said rotor, second last motion means connecting said output shaft in driving engagement with said stator, and overrunning clutch means connected between said housing and said reaction member means to allow said reaction member means to rotate only in one direction relative to said housing.

6. A rotary impact tool comprising, in combination, a housing, a motor unit mounted within said housing including a rotor and a reaction member means each mounted for rotation with respect to said housing and for limited rotation with respect to each other; hammer means mounted to rotate in unison with said rotor; overrunning clutch means mounted between said housing and said reaction member means, whereby said reaction member means rotates effectively in one direction with respect to said housing; anvil means mounted in the path of rotation of said hammer means; automatic reversing, means dependent upon the relative rotary positions of said anvil means and said hammer means for periodically reversing the direction of relative rotation therebetween, and limited lost motion means interconnected between said rotor and said anvil to cause said hammer to deliver a series of blows to the anvil in the same direction of rotation as the rotation of said reaction member means.

7. A rotary impact power device as set forth in claim 6, further characterized by said overrunning clutch being rcversible, and other reversing means for acting on said overrunning clutch to cause said reaction member means to rotate efiectively in the reverse direction relative to said housingwhen so reversed.

8. A rotary impact tool comprising, in combination, a housing; a motor unit mounted within said housing including a reaction member means and massive rotor means including hammer means each mounted for rotation with respect to said housing and for limited rotation with respect to each other; overrunning clutch means mounted between said housing and said reaction member means to limit the rotation of said reaction member means with respect to said housing effectively to one direction; output shaft means mounted in said housing for rotation with respect thereto and including an anvil portion in the rotary path of the hammer portion of said massive rotor means; automatic reversing means sensitive to the relative rotary positions of said anvil means and said hammer means for periodically reversing the direction of rotation of said rotor with respect to said reaction member means; shaft driving means interposed between said reaction member means and said output shaft whereby said reaction member means urges said output shaft in one direction; and

limited lost motion means interposed between said massive rotor means and said output shaft whereby said massive rotor means periodically hammers the anvil portion of said shaft in said ohe direction,

9. A rotary impact power device as set forth in claim 8, further characterized by said overrunning clutch being reversible, and other reversing means for acting on said overrunning clutch to cause said reaction member means to rotate effectively in the reverse direction relative to said housing when so reversed.

10. A rotary pneumatic impact tool comprising, in combination, a housing; a motor unit including a massive rotor rotatably mounted within said housing and including a hammer, and reaction member means mounted around said rotor for rotation in one direction only with respect to said housing; air inlet means to said motor unit for admitting compressed air for driving said rotor and said reaction member means with respect to said housing; output shaft means rotatably mounted in said housing and including an anvil positioned in the rotary path of said hammer; shaft driving means interposed between said reaction member means and said output shaft, whereby said reaction member means urges said output shaft in one direction; automatic reversing means sensitive to the relative rotary positions of said anvil and said hammer for periodically reversing the direction of rotation of said rotor with respect to said reaction member means; and limited lost motion means interposed between said massive rotor means and said output shaft means, whereby said hammer periodically hammers the anvil in said one direction of rotation.

11. A rotary impact device as set forth in claim 10, further characterized by manually operable reversing means and by the provision of an overrunning clutch to cause said reaction member means to rotate only in the reverse direction relative to said housing upon actuation of said manually operable reversing means.

12. A rotary pneumatic impact tool as set forth in claim 10, further characterized by said automatic reversing means comprising pressure operated reversing means.

13. A rotary impact tool comprising, in combination only a single housing, a motor mounted for rotation within said housing, means for reversing the direction of rotation of said motor, massive hammer means including a hammer impact jaw mounted within said housing and connected to said motor for rotation in forward or reverse direction with said hammer jaw describing a given arcuate path, an anvil including an anvil impact jaw mounted within said housing with said anvil jaw always within the given arcuate path of said hammer jaw, whereby said hammer jaw upon rotation in forward or reverse direction hits said anvil jaw, and automatic means associated with said hammer means causing said hammer means to intermittently hammer said anvil means.

14. A rotary impact tool comprising, in combination, a housing, only a single motor mounted within said housing for rotation and including a rotor and reaction member means, hammer means coupled to said rotor, output shaft means having an anvil meshed with a portion of said hammer means and capable of relative lost motion, and automatic reversing means to cause said hammer to oscillate with respect to said anvil and deliver a series of blows in one direction to the anvil.

15. A rotary impact tool, in combination, a housing, only a single motor mounted within said housing for rotation and including a rotor and a reaction member means, hammer means coupled to said rotor, output shaft means having an anvil always meshed with a portion of said hammer means and capable of relative lost motion, and automatic reversing means sensitive to the relative positions of the hammer and anvil to cause said hammer to oscillate with respect to said anvil and deliver a series of blows in one direction to the anvil.

16. A rotary impact tool comprising in combination, a housing, motor means mounted within said housing for rotation and including a rotor and a reaction member means, hammer means coupled to said rotor for rotation therewith, output shaft means having an anvil always meshed with a portion of said hammer means and capable of relative lost motion with respect thereto, automatic reversing means sensitive to the relative positions of the hammer and anvil to cause said hammer to oscillate with respect to said anvil and deliver a series of blows in one direction to the anvil, and means for reversing the direction of said motor to reverse the direction of said blows on said anvil.

17. In a motor for a pneumatic impact tool, a rotor member and reaction member means concentrically mounted for limited relative motion with respect to each other and spaced apart defining an annular chamber, means connected to one of said members sealing across said space at a first location, valve means connected to the other of said members sealing across said space at a second location spaced circumferentia'lly away from said first location dividing said chamber into two portions and automatically admitting air under pressure to first one and then the other of said chamber portions to produce relative motion between said rotor and said reaction member means, a hammer connected to a rotatable part of said motor, and an output shaft including an anvil portion mounted with respect to said motor for impact by said hammer.

18. A rotary impact power tool comprising in combination, a housing, a rotor mounted for rotation within said housing, a reaction member means mounted within said housing concentric with respect to said rotor for limited rotation with respect to said rotor and with respect to said housing, and means mounted within said housing causing said rotor and said reaction member means to alternately drive said output shaft efiectively v in one direction.

19. An impact tool comprising, in combination, a housing, only a single motor including a rotor mounted for rotation within said housing, a hammer connected to said rotor and having an impact delivery jaw, an anvil rotatably mounted within said housing and having an impact receiving jaw always meshed with said impact delivery jaw, automatic means controlling the motor to provide a forward power stroke and a reverse power stroke, said forward power stroke being longer than the reverse power stroke to cause said hammer to deliver a series of impact blows on the anvil in one direction only.

20. An impact tool comprising, in combination, a housing, motor means including a rotor mounted for rotation within said housing, a hammer connected to said rotor and having an impact delivering jaw, an anvil rotatably mounted within said housing and having an impact-receiving jaw always meshed with said impact delivering jaw, automatic means controlling the motor to provide a forward power stroke and a reverse power stroke, said forward power stroke being longer than the reverse power stroke to cause said hammer to deliver a series of impact blows on the anvil in one direction only, and reversible means acting on the automatic means to make the reverse power stroke longer than the forward power stroke to cause said hammer to deliver a series of impact blows on the anvil in the reverse direction.

21. An impact tool as set forth in claim 20, further characterized by said motor means comprising only a single motor. 22. A rotary power device comprising, in combination, a housing, a motor mounted within said housing and having a central member and a surrounding member spaced concentrically around the central member defining an annular chamber, a first vane connected to the surrounding member and in sliding engagement with the central member, a second vane tiltably mounted in loose engagement in a slot in said central member and in slidmg engagement with said surrounding member, the first and second vanes dividing said annular chamber into two portions, two end plates sealing the two ends of said annular chamber, one of said end plates having exhaust port means connecting said annular chamber to atmosphere, said central member having a bore connected to said slot to supply air under pressure thereto, said second vane acting as a snap action valve to control the admission of air under pressure to one or the other of said annular portions of said annular chamber depending upon the relative position of said exhaust port means and said tiltable vane.

23. A rotary power device as set forth in claim 22, further characterized by a slide valve positioned between said tiltable vane and the end plate having said exhaust port means and covering up at least a portion of said exhaust port means, and means for shifting said slide valve relative tosaid end plate in accordance with the rotary motion of said central member,

References Cited in the file of this patent UNITED STATES PATENTS 2,107,108 De Mooy Feb. 1, 1938 2,219,883 Amtsberg Oct. 29, 1940 2,425,793 Fosnot Aug. 19, 1947 2,543,979 Maurer Mar. 6, 1951 2,581,033 Larson et al. Ian. 1, 1952 2,768,546 Amtsbert Oct. 30, 1956 2,784,625 Maurer Mar. 12, 1957 2,784,818 Maurer Mar. 12, 1957 

